True and engine will warm up considerably faster if vehicle is driven than sitting at idle "warming up".

 

The "warm up" time for a heated o2 sensor is measured in seconds. An unheated sensor will begin to switch in less than 3 minutes.
The volume of fuel required to warm the coolant up to say 190 is about the same weather its sitting at idle or driving down the road. Obviously the difference is you burn more fuel driving down the road so therefore it happens faster, but from the perspective of water vapor (which started this nonsense) there is little if any difference.

 

HO2 is OBD2. This car is a 92 which it looking for a temperature increase and the O2 to become active. If ECT is slow to increase because of low coolant level or faulty thermostat. O2 sensor is slow to overcome 450mv to send ECM into closed loop ecm will continue to overfuel engine. Then the ECM will take over fuel control. The injectors are aimed to spray fuel at intake valve. Since this this is a batch fire car, injectors are spraying fuel into cylinder 4 times per revolution. Carbs as long as choke is on its overfueling. The idea of letting it "warm up" was from when the carburetors and fuel that was available wasn't very good. Of course an added benefit the glass would be clear.

 

Ok, what does this have to do with water vapor ?

The bottom line here is that water vapor is somewhere around the 10-15% content of exhaust gas. In other words, regardless of the temp of the engine, there's a lot of water vapor in the exhaust. So much so, that there's actually a bleed hole in every muffler. So this bs about how allowing an engine to run, then shutting it off, is somehow causing premature failure of the exhaust is silly. Any time the engine is running (warm or cold) water vapor is passing through the exhaust. The only way to prevent water vapor from contaminating the insides of an exhaust system, is to never run the engine.

 

its worth mentioning that when you see a muffler ruined by rust that seems to originate from the bleed hole, it isn't because water leaks out of the bleed hole, Its because the edges of the sheet metal dont have any galvanization (or other rust protectant) where there's a hole punched through it.

 

Couple of things from real world shop experience.

When an engine is started cold, the gasoline mixture is set richer. It s set richer because it is not the liquid that burns, but the atomized vapors. When it is cold and the engine heat is not helping the fuel vaporize, more liquid fuel is dumped in so that more vapors will be available. This is when it's most likely to wash the cylinder walls and get past the rings. I remember a corvette at the car dealer that was moved around the lot every few days - by the time it was sold it had made about a quart of oil (gasoline past the rings). This pertains to frequent, very short run periods from a cold start.

Running an exhaust shop many years ago, we saw every exhaust failure you could imagine. The short trip around town cars always went through exhaust much sooner than long trip highway cars. The condensation in the pipe is worst when the pipes are cold and the hot exhaust gasses creates a ton of condensation inside the exhaust. You will notice they drip like crazy shortly after startup and some will actually have water dump from the tail pipe as they pull away from a light. As the exhaust heats up, this water evaporates much quicker. So, if the exhaust was fully up to temp, there will be far less water in it than if it was just run for a few minutes and turned off. It's not noticed as badly in the factory stainless systems, but once you get an aftermarket "aluminized" pipe on there boy do you see the difference.

Condensation also builds inside an engine that is started and stopped just to run it in the winter. It get's warm, it's cold it sweats - that's a fact. This can be seen in the creamy oil that will accumulate on the bottom of some oil caps. However, once the oil is brought fully up to temp and kept there for a while, that moisture will burn off.

So, it is 100% true that engines started for short periods of time in the winter build up moisture and acids in the engine and exhaust. If you're going to run the engine fully up to temp, you'll reduce a lot of this, but when people just let it run for 5 or so minutes once a week thinking they're doing it a favor, they are not.

This can easily be researched from reputable authorities - this thread has really gone into the tank with all the bickering and snarkiness. It's kind of a bummer to see this happening more and more on the forum.

 

If this discussion is going to continue, then its time to assign a time frame which would be "to short" to start and run an engine. Its worth mentioning that the op said he ran his cars for half an hour. Maybe some of the "reputable authorities" your speaking of have already done so. While your at it, maybe assign a time frame for the "exhaust to heat up".

 

Wow! Guys I didn't mean for my post to go off the rails here.
Yes, I normally when it's a good day I take the cars out and drive them for about 20 to 30 miles or so and on the highways since I live in a rural area.
The time that I ran it this time was I just couldn't get away for a longer drive. No, I never just start my car and shut it off after ten minutes. This time I started it I brought it up to operating temp and so much so that the cooling fans came on. These two '92's go out on good driving days here in Texas. And again no, I don't just start them and shut them off after ten or so minutes.

 

Don't give it a second thought when a thread seems to digress on unrelated issues. Some of the folks on here use debate to help understand a particular topic. This seems to be one of those times.

 

You need to bring it to full operating temp to clear moisture.

 

You need to bring it to full operating temp to clear moisture. After it reaches full operating temp check your exhaust tips. You will see they have dried, white exhaust is gone. If you still have moisture or white exhaust better check head gaskets.

 

[left]You're exactly the snarky type of person person I reference - look at most of your posts - they're just confrontational rather than helpful.

If you actually read my post you'll see i clearly differentiated times as well as gave real world examples to contribute to the thread. I'm sure you will come back with another sarcastic comment but hey - it's a free country - have fun.

 

You spoke in vague generalities.
The closest you came to specific was the "5 minutes or so once a week" sentence.
By the way, confrontation is an integral element of opposing positions. You don't have to let it bother you.

 

Just to put this thread to rest it turned out to be a failing ICM. While I was there changed the 26 year old coil too while I had the two out.

 

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That would sure do it. Glad to hear the problem is solved. Hopefully the exhaust dosent fall off or the engine blow up though .... you know, from warming it up. Lol.

 

most of the moisture in this thread seems to be coming from a pissing contest....and yes, I know I should keep my opinions to myself.

 

LOL ... yeah .

 

My 93 did the same thing a couple of weeks ago, it was running fine and one morning it wouldn't start, just crank over. The car had been sitting overnight when this occurred. While my wife engaged the starter, I tried Starting Fluid in the Throttle Body and nothing. That suggested a No Fire Condition. I ordered a new Coil, Ignition Control Module and Heat Sink from Chevrolet, and changed out these 25 year old parts. Was this the fix? I don't know, but I feel better having the new parts and it has started 40-50 time with no issues.